1. Field of the Invention
This invention relates to an improved method for the elimination or reduction of contaminant hydrocarbons, e.g., in soil or groundwater, by biodegradation utilizing a bicarbonate.
2. Information Disclosure Statement Including Description of Related Art
The following information is disclosed in accordance with the provisions of 37 CFR 1.56, 1.97 and 1.98.
An environmental problem that has been receiving increasing attention is the contamination of soil and groundwater by hydrocarbons which have leaked or spilled from storage, pumping, production, transportation and other facilities involving the handling of such hydrocarbons.
It is well known that certain microorganisms are capable of eliminating hydrocarbons by utilizing them in their metabolism. Some of these microorganisms may be indigenous to the soil or groundwater into which hydrocarbons may spill or leak and spontaneously act to eliminate all or part of such hydrocarbons. In this connection, it has been found that various techniques increase the activity of the microorganism in reducing the content of the contaminating hydrocarbon, e.g., the addition of nitrogen or phosphorus-containing nutrients or the aeration of the soil or groundwater. In other instances, such hydrocarbon-metabolizing microorganisms may be added to the soil or groundwater to enhance the destruction of the hydrocarbons.
Attention is directed to the following related art which may be pertinent to the invention claimed herein.
U.S. Pat. No. 3,616,204, issued Oct. 26, 1971 to Linn, discloses the restoration of soil contaminated by hydrocarbon spillage by first disturbing the soil, as by plowing or discing, followed by inoculation with a hydrocarbon-consuming microorganism while controlling the nutrient and oxygen content of the soil. A nutrient medium may be applied comprising an aqueous solution of various salts including carbonates and sodium, potassium and ammonium salts.
U.S. Pat. No. 3,843,517, issued Oct. 22, 1974 to McKinney et al., discloses methods for elimination of oil slicks including the steps of absorbing a culture of hydrocarbon-consuming microorganisms on a carrier such as a clay and applying the microorganism-containing carrier to the oil slick. The microorganisms are cultured in an aqueous nutrient medium of salts, e.g., sodium carbonate.
U.S. Pat. No. 4,042,495, issued Aug. 16, 1977 to Marconi et al., teaches the removal of oil hydrocarbon pollutants from the surface of water by scattering over the polluted surface solid particles of nutrient salt containing nitrogen and phosphorus in a form assimilable by microorganisms capable of metabolizing hydrocarbons. The salt particles are coated with paraffin to render them buoyant and slowly soluble in water. Ammonium bicarbonate is included in the formation of tablets of the nutrient salt but is thermally decomposed to increase the porosity of the tablets prior to their utilization.
U.S. Pat. No. 4,124,501, issued Nov. 7, 1978 to Yen et al., discloses the purification of oil shale retort water by adding anaerobic bacteria to increase cell biomass and reduce sulfate ions to sulfide. The cell biomass is then aggregated into a flocculent mass and removed. Table 1 of the disclosure indicates that bicarbonate ions are included in the solids content of the oil shale retort water.
U.S. Pat. No. 4,401,569, issued Aug. 30, 1983 to Jhaveri et al., teaches a method and apparatus for treating hydrocarbon and halogenated hydrocarbon-contaminated ground and groundwater utilizing microorganisms, the growth of which is enhanced by the addition of nutrients such as sodium carbonate.